Project Summary A central goal of biology is to understand how behavior can evolve and how behavioral differences can ultimately lead to reproductive isolation and the evolution of new species. The search for the genes that cause reproductive isolation, so-called `speciation genes', has recently led to the important discovery of multiple genes that cause hybrid sterility or inviability. However, it is widely acknowledged that prezygotic isolation and behavioral isolation typically arises earlier during the speciation process. Few studies have been able to identify the precise genomic changes causing shifts in behavior that contribute to reproductive isolation. The Drosophila athabasca complex is an ideal system for investigating the evolution of behavior, its genetic basis and role in the evolution of new species. Drosophila athabasca is comprised of three very recently formed races that have dramatic differences in male courtship song and female preference. By taking a multi- tiered approach we are combining 1) an extensive rangewide population genetic analyses of the three races with 2) QTL mapping of race-specific male courtship differences with 3) functional characterization and experimentation of putative genes underlying these evolved differences in male behavior. Population genetic analysis allow us to identify when these three races formed and genome scans will identify regions of the genome that are contributing to race formation. QTL analyses will locate genomic intervals that harbor differences in race-specific male courtship behaviors. The combination of the QTL and genome scan analyses will provide regions of the genome for targeted investigated of genes driving changes in behavior. This combined analysis will allow for the characterization of the genetic basis of behavioral divergence in this incredibly recent speciation event and identification of the causative behavioral gene(s) that fuel the evolution of new species.